Mooring systems of the type comprising a tanker or the like as well as a buoy are known in many forms. The buoy can have anchoring means in the form of chains or in the form of pivotable arms. Between tanker and buoy a connection has to be made, such that tanker and buoy can follow the movements imparted to them by wind and waves independent of ech other or by connecting the buoy to the tanker in such a way, that the buoy follows the movement of the tanker entirely. To this end it is known to provide the tanker with an outwardly extending arm and to move the buoy out of the water and give it a releasable connection with said arm. Examples of said prior art solutions are found in U.S. Pat. No. 3,572,408 and German Patent Specification No. 2,752,266. Accorrding to U.S. Pat. No. 3,572,408 the connection is made by lifting the anchoring means out of the water by increasing its buoyancy and bring its connecting means in the right position by means of a lifting line, the connection being finally performed by radially inwardly moving pistons, which enclose a spherical universal joint. It will be clear that during operation this joint is under permanent movement. According to the German Specification No. 2,752,266 the buoy is lifted out of the water by means of a winch and moved into the forkshaped opening between two outwardly extending arms and locked in place by means of hydraulic locking cylinders. According to said prior art a quick disconnection is possible, in that problems can arise if the flow lines passing from the vessel to the buoy are not disconnected first. Moreover, said quick release connecting systems require maintenance.